Ezetimibe containing β-lactam structure is a novel cholesterol-lowering drug which was developed by Schering-Plough and approved for marketing by US Food and Drug Administration (FDA) at the end of 2002. It inhibits intestinal absorption of exogenous cholesterol to lower the concentrations of low density lipoprotein-cholesterol and total cholesterol in plasma. When it was used alone in clinic, it can lower low density lipoprotein-cholesterol (LDL-C) and significantly lower total cholesterol. The cholesterol-lowering effect obtained by Ezetimibe in combination with statins corresponds to that obtained by eight times of dose of statin.
EP720599 firstly disclosed the synthetic method for Ezetimibe:

Since then, several synthetic routes have been reported, for example, U.S. Pat. Nos. 5,856,473, 5,739,321, EP 1137634, EP 720599, WO 1995/08532 and EP 0720599 provided the synthetic routes of Ezetimibe.
In the methods which have been reported at present, equivalent chiral oxazolidinone auxiliary or chiral (S)-hydroxy-butyrolactone was used as starting material for constructing key chiral C-4 in four-membered ring of lactam, which was not economic and environment-friendly and of high cost.